Helicopter main landing gears typically may weigh 2 to 3 percent of the gross weight of the aircraft, and heretofore the landing gears have served no useful function during flight. A conventional helicopter landing gear is disclosed in U.S. Pat. No. 1,912,840 to Havill wherein it is shown that the upper telescoping strut of the landing gear is connected to the airframe in such a way as to prevent any significant in-flight vibration absorbtion by the landing gear assembly. While the lower telescoping strut disclosed in the Havill patent is mounted for relative movement with respect to the airframe, the connection between the upper and lower telescoping struts again prevents significant vibration absorbtion during flight.
As shown in U.S. Pat. No. 2,487,653 issued to Heintze, it is known to provide a helicopter with means in the mounting of the blades of the helicopter for dampening and/or absorbing vibrations and isolating such vibrations from the airframe; however, again the landing gear assembly disclosed in the Heintze patent performs no useful function during flight.
According to the principles of the present invention, during flight, main landing gears of a helicopter are suspended by a tuning spring from the airframe to provide limited relative movement between the landing gears and the airframe. Upon landing, the landing gears are forced into rigid contact with the airframe, and thereafter the landing gear shock absorber functions in the conventional manner, to at least partially isolate the airframe from the shock associated with landing. In this manner, the main landing gears, which are of course indispensible elements of the helicopter for purposes of landing, also provide a necessary function during flight.
It is therefore the main object of the invention to provide a helicopter landing gear which is mounted in a novel manner to the helicopter airframe so as to provide a mass which will respond to and balance detrimental vibrational forces acting upon the airframe during flight.